Insect resistant geotextile

ABSTRACT

The needlepunched nonwoven synthetic material prevents the insects from burrowing through by presenting the insects with overlapping, randomly placed fiber layers. The insects attack the ends of the fibers, going from fiber to fiber until they are trapped within the fabric layers. Water permeability is enabled while preventing insects from penetrating the material.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

[0001] The present application is a continuation in part of U.S. Ser.No. 09/413,808 filed Oct. 6, 1999, which claims the benefits under 35U.S.C. 119(e) of provisional patent application serial No. 60/103,285,filed Oct. 6, 1998. This application incorporates by reference, asthough recited in full, the disclosure of copending application Ser. No.09/412,808 and provisional application 60/103,285.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention discloses a geotextile resistant to insectpenetration, having application in areas such as yards, playgrounds andhome protection.

[0004] 2. Brief Description of the Prior Art

[0005] Ants, and other insect, colonies established in lawns,playgrounds and parks, or other recreational areas can cause damage,attack people and animals and make the use of outdoor areas lessenjoyable. The imported fire ant has been a problem for years in thesoutheastern United States and has systematically moved north and west.In an attempt to control their population, fire ants are treatedextensively and regularly with various pesticides. Solutions to theproblems, which are alternative to pesticide treatment is sought whichcan reduce or eliminate the problems caused by fire ants and otherpests, and which solutions are long term in effect do not have highcosts associated with them.

SUMMARY OF THE INVENTION

[0006] Because of their lower manufacturing costs, nonwoven fabrics canbe economically used as barriers in high value landscapes to keep soilinsects within subsurface treatment zones, thereby improving theefficacy of treatments. In addition, subsurface soil barriers may createa non-preferred habitat, which results in the migration of pest to lesssensitive areas. For example, fire ants will either build shallower,more easily treated (or easily frozen in frigid weather) nests, orestablish nest sites in areas without the fabric. Installing the fabricin playgrounds and schoolyards would reduce insect colonization andpesticide input in these sensitive areas. The fabric placed under mulchin landscape beds and trees or shrubs can have the added benefit ofpreventing weed emergence.

[0007] The needlepunched nonwoven synthetic material prevents theinsects from burrowing through by presenting the insects withoverlapping, randomly placed fiber layers. The insects attack the endsof the fibers, going from fiber to fiber until they are trapped withinthe fabric layers. Water permeability is enabled while preventinginsects from penetrating the material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The advantages of the instant disclosure will become moreapparent when read with the specification and the drawings, wherein:

[0009]FIG. 1 is a chart indicating the various properties of materialsfor use in the disclosed fabric;

[0010]FIG. 2 is a cutaway side view of the material being used to coveran area of land;

[0011]FIG. 3 is a cutaway side view of the material laid out to cover afoundation;

[0012]FIG. 4 is a cutaway side view of the material covering thefoundation and house;

[0013]FIG. 5 is a flow chart of the method of using the material to wrapa house; and

[0014]FIG. 6 is a flow chart of them method of using the material tocover an area of land.

DETAILED DESCRIPTION OF THE INVENTION

[0015] Ants and other insect pests that establish nests in lawns,playgrounds and parks, or other recreational areas can cause damage,attack people and animals and make the use of outdoor areas lessenjoyable. The imported fire ant has been a problem for years in thesoutheastern United States and has, recently, moved north info Virginiaand west to California. In an attempt to control their population,pesticides have been used extensively and regularly, however affordablealternatives are sought that are long term in effect and environmentallysafe. Another pest, termites, which attack wooden structures in mostareas of the US, creates extensive damage to public and privateproperty. The termite and the fire ant problem are most severe in theSoutheastern US because of weather conditions favorable to theirsurvival. According to Commerce Department statistics, the South is byfar the largest market for housing in the US. Although the nestinghabits of some insects, including termites and ants, make theapplication of geotextile technology attractive, the prior art problemlay in finding a mechanism to prevent the insects from eating their wayup, through the fabric while maintaining proper water drainage controlabove the fabric.

[0016] Geotextiles are water permeable textiles frequently used inconjunction with soils or rocks as an integral part of man madeprojects, providing cost effective substitutes or enhancements to othermaterials in civil engineering projects. The area of geotextile fabricshas been a strong part of the American textile industry since the 1970'sand few textile markets have recently enjoyed the tremendous growth thatthe geotextile market has experienced. The nesting habits of insectpests, such as imported fire ants, is now seen to make the applicationof geotextile technology a logical and useful solution to their control.Application of a successful geotextile material to prevent infestationof pest insects such as ants would be environmentally beneficial byreducing, or eliminating, the need for pesticide use. Although the areaof geotextile fabrics offers an environmental acceptable solution to theproblem of insect control, such as fire ants, this technology has not,to date, been used to combat infestations of insects in lawns orrecreational areas. The primary reason for the absence in thisapplication is the ability of ants, and other insects, to eat throughmany materials. Therefore, the construction and composition ofgeotextile required for such an application differs considerably fromthat previously incorporated in prior art uses.

[0017] Presently geotextiles have been used in the areas of separation,filtration, drainage, and reinforcement. Separation places a geotextilebetween dissimilar materials so that the integrity and function of bothmaterials can remain intact or be improved. Geosynthetic filtrationfabrics allow flow of liquid across the surface while limiting soilloss. The relationship between allowing heavy water flow or limitingsoil passage depends on the application and the construction site. Thedrainage or transmission function refers to passage of water within theplane of the fabric. Geotextiles used for reinforcement improve thestructural stability of soil. The textile, in all cases, improves theshear strength of the system and absorbs tensile stresses.

[0018] The use of fabrics in the building and housing constructionindustry in the US is now limited to house wraps, some soilreinforcement and decoration of housing interiors. Housing contractorsuse Styrofoam board material or woven steel mesh to line housefoundations to prevent termite access to the foundation. Although thewoven steel mesh is successful in preventing termites from entering astructure, both production and installation is expensive. Textile use toprevent ant or termite invasion is generally limited to wrapping theroot systems of the plant in nursery pots. Textile sheets have also beenused to replace plastic for garden and walkway weed prevention,providing the advantage of drainage while reducing the weed growth.

[0019] Depending on the method used to construct the fabric and theintended end use, the geotextile ranges in weight from approximately 3.5to 60 ounces per square yard. Of the three methods used for fabricconstruction, weaving is the slowest and most labor intensive, requiringat least four (4) processes to produce the fabric. Knitting is one orderof magnitude faster for fabric production, however geotextiles fabricsrequire the same numbers of processes as are needed in weaving. Nonwovenis two orders of magnitude faster in full-scale production than weavingand needs only two or three processes for fabric production. A nonwovenis as a textile structure consisting of a consolidated mat, or web, offibers produced by bonding or entangling fibers or filaments throughmechanical, chemical or thermal means. The properties of nonwovenfabrics lend themselves most easily to their application for theprevention of ant and other insect infestation in subterranean in theweb.

[0020] Needlepunching is the most frequently employed method of nonwovenfabric consolidation, providing a mechanical method of web bonding tointerlock fibers and tufts of fibers by entanglement and fiber friction.Entanglement of the fibers occurs as barbed needles in a needlepunchmachine (or needle loom) penetrate the fiber batt to carry tufts offibers from one layer to another without disentangling the fibers whenneedles are withdrawn. The structure of the needle determines needlingefficiency, quality of finished product, and physical characteristics ofthe fabric. The needle blade penetrates the fiber web and, with the aidof the barbs, entangles the tufts of fibers. The barb transports andentangles tufts of fibers through the batt. To accommodate syntheticfibers, barbs were designed with rounded edges, best suited for productsmanufactured from delicate or fine fibers, and where excessive fiberdamage would be detrimental to the useful life and tensile strength ofthe felt.

[0021] For a given needlepunch density, a smaller barb size, with lesscapability for fiber transport, would produce a fabric of greaterthickness and loftiness. Such a fabric structure could provide a moredifficult barrier for burrowing insects to breach, but the fabrictensile strength suffers as a result. Lowering the amount of barb“kick-up” and increasing the frequency of needle penetrations per squareinch achieves higher tensile strengths as well as a smoother fabricsurface but it decreases general permeability. Regular barb spacingprovides uniform interlocking of the felt from top to bottom while amedium spaced barb, about 0.05 mm per barb closer, can carry more fibersper stroke with a lower penetration depth than the regular spaced barb.Close barb spacing decreases felt thickness.

[0022] The advantage of using close barb spacing is that all the barbsenter the felt with a relatively small amount of penetration depth ascompared to a regular spaced barb. Generally, close spaced barbedneedles are used for maximizing needling efficiency with minimal needlepenetration. Minimal penetration is essential in high throughput loomspeeds, where needle deflection is a concern, because less penetrationmeans fewer chances of encountering resistance in the web. Reduced barbspacing produces fiber bundles distributed closer together with a denserfelt as the net result.

[0023] Nonwoven fabrics are also unique because their production linescan produce random and more easily controlled void spaces in the fabric.In knits and wovens, voids are determined entirely by the size, andstiffness of the constituent yarns. Further, since nonwovens areproduced directly from fibers, they can easily be produced according tothe desired thickness. The controllable properties of nonwoven fabricslend themselves most easily to their application for the prevention ofant and other insect infestation in subterranean environments.

[0024] The most common types of web formation in nonwovens are air-laid,wet-laid, or carded. Wet-laid, or extruded web formation, will notproduce maximum results in insect resistance, while air laid and cardedboth provide optimum prevention. Wet laid nonwovens are very thin andhave a tissue-like fabric character and are not as tough as dry formedfabrics. These nonwovens are more easily torn and provide a very flat,relatively uniform surface for the insects to attack by chewing. A weboriented in only one direction will be uniform, but lack strength inother directions because it does not have omnidirectional (isotropic)fiber orientation, as well as eliminate the zigzag fiber orientation toinhibit insect penetration. Fibers in the web are consolidated either byhigh velocity water jets (hydroentanglement), high temperatures (thermalbonding), barbed needles (needlepunch) or other methods bonding tosecure the fibers in the web.

[0025] All geotextiles are characterized by performance and index tests.A performance test attempts to predict geotextile performance in theenvironment of intended use; an index test measures a physical propertyof the geosynthetic without consideration of specific intended use.Tensile properties are evaluated in geotextiles to determine effects ofstress and strain forces on the fabric. Tensile performance is measuredby ASTM specified standards using constant rate of elongation testsincluding: grab breaking load and elongation test, wide strip test, andperformance strength by wide/strip tensile method. Puncture and burstresistance is measured by a rod puncture test and diaphragm-burstingtest respectively. Tear resistance can be measured using the trapezoidtear test.

[0026] To examine the feasibility of applying specially constructednonwoven geotextile fabrics to prevent or inhibit infestation byinsects, an initial determination was the most effective, commerciallyavailable fiber to use for the construction of the fabric to preventpenetration. This was determined by considering several factors. Theminimum threshold level of fabric density for each component fiber typeto prevent penetration of the fabric by fire ants was critical. Theeffects of the number of needle punch density (consolidation techniquefor fabric production) of a nonwoven fabric on penetration of the fabricby fire ants were then taken into consideration, as well as the fabricdegradation caused by soil and mulch. These foregoing factors wereconsidered, along with material cost, to determine the optimum materialand cost associated with the construction this fabric.

[0027] Permeability and opening size are important considerations forwhen using the nonwoven for nesting preventing due to the drainage orfiltration considerations. Permeability is defined as the flow rate,under a differential pressure, of a fluid (usually water) through ageotextile. For application to insect penetration inhibiting fabrics,the fabric must have pore (opening) sizes that are too small and toodiscontinuous to permit penetration by insects such as ants. At the sametime, the fabric must allow an acceptable flow rate of water through itto drain standing water from its surface where it is applied. Therequired permeability will be influenced by the end use and shouldfollow the site required standard industry requirements as known in thegeotextile field. Definitions of the types of geotextiles known in theindustry are defined in the Dictionary of Fiber and Textile Technology,Pgs. 71-72, Hoechst Celanese Corporation, 1989, which is incorporatedherein as though cited in full.

[0028] The size of openings in a fabric can be compared based on theapparent opening size test (AOS) or by photomicroscopy. The AOS testrequires the use of beads of various diameters to be applied to thesurface of the fabric to fill pore opening in the fabric surface. AOS ismost widely accepted for woven fabric rather than for nonwovens.

[0029] A critical step in manufacturing any fabric is selection offiber. Some fiber types, which can be considered for such a syntheticgeotextile product, are also environmentally desirable because they canbe produced wholly or substantially from recycled materials such asplastic soft drink bottles or plastic grocery bags. Polyester,polypropylene, polyethylene and polyamide are example materials for usein the disclosed application and other similar materials, commonlyapplied to subterranean applications, can also be incorporated herein.The flexible, synthetic materials must be resistance to soildegradation, microorganism growth and have tensile characteristicssufficient to prevent tearing or puncturing during the specificinstallation. Any of the fibers used should be water resistant and havea long life to make them ideal for insect control application.

[0030] Polypropylene, as is well known in the art, is polymerized fromthe propylene monomer in the presence of an organo-metallic catalyst. Inthe reaction, the catalyst breaks the secondary bond and causes a chainreaction to produce the polymer. The properties of polypropylene, suchas melting point and density, are dependent on the placement andregularity of placement of the methyl (CH3) groups. Atactic describesthe structure in which the placement of methyl groups is irregular.Isotacticity signifies that the methyl groups are on one side of thechain, and syndiotacticity indicates that methyl placement alternatesregularly from side to side. The isotacticity index, which is thepercentage of isotactic polypropylene in the polymer, is always higherthan 90% for commercial polypropylene.

[0031] The chart of FIG. 1, comparing the properties of polypropylene,polyester and polyamide, shows that the melting point of polypropyleneis about 150° F. lower than that of polyester. The chart is taken from“Textile World Manmade Fiber Chart 1994” by McAllister Isaacs III.Textile World, 1994. This means that the energy required to thermallybond polypropylene is less than the energy required to bond the sameamount of polyester. Polypropylene is approximately 52% lighter thanpolyester's specific gravity of 1.38 g/cc.

[0032] The following tests at Auburn University involving both theDepartment of Entomology and the Department of Textile Engineeringillustrate that certain constructions of nonwoven polyester fabrics areimpenetrable by fire ants and that not all nonwoven polyester fabricswill resist penetration by the ants. Imported fire ants were use as theinitial test insect, because of the need and interest in controllingthis pest, and their ability to breach barriers (e.g. roof linings,electrical insulation).

[0033] The dual tests were performed under identical conditions, withand without water present in the bag. All of the following tests wereperformed by placing the ants in bags using material describedspecifically in each Example. The nonwoven fabric was produced using amedium barb and about 550 punches per square inch. Both nonwoven fabricswere made from 1.5 denier polyester fibers, approximately 1½″ in lengthand needled with a top punch needling process using lightweight feltingneedles. As no food was placed in the bag during any of the tests, thecolony was forced to chew through the bag to get to food. The bags weremanufactured to prevent a small colony (>750 worker ants) from escaping.

EXAMPLE I

[0034] An extruded nonwoven, such as Tyvek® was used to form a bag whichwas sealed to prevent the ants escape. The ants penetrated the extrudednonwoven within two (2) hours.

EXAMPLE II

[0035] A bag was formed using a nonwoven polyester fabric of 130 g/m² (4oz/yd²) and the ants were placed inside the bag without access to water.The colony was unable to penetrate the 8 oz. fabric and most died within14 days.

EXAMPLE III

[0036] The ants were placed in a duplicate bag of the foregoing 4 oz.with water, although this placed the fabric at a disadvantage. After 23days, the ants were still unable to chew through the 8 oz. fabric.

EXAMPLE IV

[0037] The colony was sealed into a bag of 85 g/m² (2.5 oz/yd²) nonwovenpolyester without water. The ants were unable to chew through thelighter weight polyester without the presence of water.

EXAMPLE V

[0038] The colony was sealed into a bag of 85 g/m² (2.5 oz/yd²) nonwovenpolyester water. In contrast to the 8 oz. material, the lighter weightpolyester fabric was chewed through within six (6) days, which indicatesthat there is a fabric density threshold above which fire ants cannotpenetrate.

EXAMPLE VI

[0039] A termite infested small wooden structure was lifted from itsresting place to ensure that a termite colony was directly underneath.Several days later the structure was again lifted to ensure that thecolony had not left due to the initial disturbance. A sheet of fabric(2.5 oz/yd²) was placed between the termite colony and the base of thewood structure, but did not wrap around the sides. The wood structurewas sunken approximately {fraction (1/3)} of the depth of its base. Oneweek later, the colony had left and there was no termite activity.

[0040] Initial test results have shown that the lighter weight materialwill retard the burrowing of fire ants through the fabric when water ispresent. In the absence of a water source in the fabric case, however,ants are unable to escape through the lighter, 2.5 oz., fabric. Theheavier fabric was impenetrable to the insects even when water waspresent for them inside the fabric case. The one exception to theresults for the heavier fabric sample occurred because of a fabricationdefect in the fabric bag side seam. This reinforces the inability of thecolony to eat through the 4 oz fabric. The results show that there is afabric density threshold of about 4 oz. per square yard above which fireants cannot penetrate a fabric without starving first. This indicatesthat in earth based colonies, the ants would chose to abandon anattempted nesting site a distance from food or water rather than die ofdehydration or starvation. Nesting sites established above thegeotextile layer are too shallow to support the colony in extreme heat,cold or temporary flooding from heavy rains. Termite penetrationpatterns are similar to that of ants.

[0041] To provide new construction with maximum protection againstinvading insects, once the foundation area 26 is cleared, the nonwovenfabric 20, as illustrated in FIGS. 3 and 5, is placed within thefoundation area 26. The foundation 24 is then placed on top of thefabric 20 and the house 26 is constructed, as seen in FIG. 4. The fabricis then wrapped over as much of the house 26 as desired and thestructure completed. In FIG. 3, the fabric 20 covers only thefoundation, while in FIG. 4 additional fabric 20 is added around thehouse 26. Although FIG. 3 illustrates the extra fabric pulled away fromthe foundation 24, the material can be cut to extend only slightlybeyond the foundation 24 and additional added to complete the coverageof the foundation 24. It should be noted that the disclosed fabric canbe used with slab foundation as well as houses having a basement, withany differences in the installation being obvious to those skilled inthe art.

[0042] When used to protect yards, playgrounds, etc. from ants, theground is dug down within the desired periphery and the fabric placed onthe cleared surface. The depth to which the soil is removed is a matterof landscaping and/or preferences, with the average being at least 6 to8 inches below the placement of the surface. In instances where shrubsare being planted, the depth beneath the shrub can be greater, forexample 18 inches, with the depth gradually decrease until the itreaches 6 to 8 inches. In applying the fabric 20 to the ground 12, thestrips of fabric 20 must be overlapped to some extent. The overlap candepend upon potential infestation, end use and cost. An overlap must bepresent to prevent insect penetration and a minimum of ⅛ inch ispreferable. Once the excavated ground 12 covered, the topsoil 14 isreplaced and/or added.

[0043] The non woven construction of the disclosed fabric prevents rootpenetration, thereby requiring planning for large trees or shrubs. Sincethe tree or shrub will die without sufficient root expansion, a holemust be cut within the fabric and a hole dug, beneath the access hole,within which to plan the tree. The area would then need to be treatedwith insecticides to prevent insect infestation.

[0044] When large areas of land are being protected and the insectstrapped beneath the fabric, food deprivation is relied upon to preventnesting. For the fabric to act as an effective barrier, the viscousenergy dissipated by the chewing ant or insect exceeds must energysupply. When the ants must travel too far to transport sufficient foodto build the colony, colonies are confined to the periphery of theprotected areas, therefore requiring the areas of greatest protection tobe along the periphery of the covered area. When covering large areas,such as housing developments, heavier fabric can be used along theperiphery while thinner material can be used toward the center of thearea. Thus, once the total area is determined 60 and the top soilremoved 62, the area to be covered is divided into two sections; anouter section and an inner section. The outer section, which extendsfrom the outer periphery toward the center a distance greater than theinsect would travel to set up a colony is covered with a first, orheavier, fabric 64. The inner section would cover the remaining interiorarea and covered with a second, or lighter, fabric 66. The top soil isthen replaced over the entire area 68. The distance an insect wouldtravel would be known to those versed in entomology. The minimum fabricthickness required is determined by the fracture toughness of the fibersand on the type and thickness of the cross-section.

[0045] When food is not limited, the minimum thickness will depend onthe behavior of the insect group, which often emulates the behavior ofcorrosive viscous liquids. On a micromechanical scale, the length of themandible moment arm, the acuteness of the mandible bite surface wedgeand the fracture toughness of the surface being attacked determine thecorrosive action.

[0046] The nonwovens prevent insect penetration due to the insect'sinstinct to attack an end of fiber. In a woven, there are viewer endsand a multiple of openings. In a nonwoven the insects see only amultitude of short, jumbled fibers. The each fiber layer forming thenonwoven provides a multiplicity of attack points created by theinherent fiber orientation and characteristics. The insects cannoteasily work their way directly through the fabric, but rather travel thezigzag path of the fibers forming the nonwoven and getting lost in thecross laid structure. Since the fiber structure within the material ison a predominately horizontal plane, the insects following the fiberstravel horizontally vs. vertically, or from underside to topside, of thematerial. From an insect perspective, they see only fiber ends, not aflat sheet. Materials, such as Tyveck®, fail to retain insects due tothe presentation of a flat sheet rather than the high population,randomly oriented jumbled fiber presentation of the nonwoven. Thepresentation of a jumble of randomly oriented fibers is eliminated oncea bonding material is introduced making it critical, to obtain maximumresults, for the material to be only needlepunched. Additionalpenetration resistance is obtained by increasing the fiber diameters tobe equal to, or greater than, the diameter easily accepted by themajority of the insect's mandibles. The diameter would vary inaccordance with the type of insect and can, in some instancesrealistically, be directed only to the “average”. At some point thediameter sizing would affect adversely the cost and characteristics ofthe fabric.

[0047] Mathematically, this action can be modeled by the formula used todescribe containers for extremely corrosive or hot liquids such as thatdescribed by the viscous dissipation formula${\rho \quad \frac{\left( u^{2} \right)}{t}} = {{{- u}\quad \frac{\partial P}{\partial z}} + {\rho \quad {f(u)}} - Q_{visc}}$

[0048] Where:

[0049] ρ=liquid/organism density;

[0050] P=pressure;

[0051] D=expression for a first derivative in Calculus;

[0052] u=liquid/organism internal energy;

[0053] Dt=derivative with respect to time;

[0054] □=partial derivative;

[0055] z=fabric thickness direction;

[0056] ρf=ρ times f(u) where f(u) is a function of u;

[0057] Qvisc=viscous dissipation loss

[0058] In cases where Qvisc remains greater than D(u2)/Dt, the insectswill not be able to penetrate the fabric before they die.

[0059] Successful use of nonwoven geotextiles as a barrier to importedfire ants, suggests their use in other applications such as termitebarriers for structures, confining soil insect pests such as molecrickets and white grubs to treatable subsurface soil zones. Other thanprevent fire ant nesting, the geotextile can be used for fire ant proofwraps for root balls for nurseries within the imported fire antquarantine, and seals for electrical switch boxes. All theseapplications could reduce or eliminate pesticide applications.

What is claimed is:
 1. A needlepunched nonwoven synthetic materialhaving random fiber positioning and irregular voids and producingsufficient weight and loft to prevent insects from penetrating saidmaterial while enabling site required moisture permeability.
 2. Thenonwoven material of claim 1 wherein said nonwoven is air-laid.
 3. Thenonwoven material of claim 1 wherein said material is carded.
 4. Thenonwoven material of claim 1 wherein said material is needlepunched atabout 550 punches per square inch.
 5. The nonwoven material of claim 1wherein fibers within said material are 1.5 denier polyester fibers,approximately 1½ inches in length.
 6. The nonwoven material of claim 6wherein said material is needled with a top punch needling process usinglightweight felting needles.
 7. The nonwoven material of claim 1 whereinsaid fabric weight is at least about 2.5 ounces per square yard.
 8. Thenonwoven material claim 7 wherein said fabric is about 4 ounces persquare yard.
 9. The nonwoven material of claim 1 wherein said nonwovenis air-laid.
 10. The nonwoven material of claim 1 wherein said materialis carded.
 11. A method of preventing insects from entering into apredetermined area using a fabric formed of an unfused, needlepunched,nonwoven synthetic material having randomly arranged fiber orientationcreating irregular voids, said fibers having an average fiber diameterat least equal to the diameter easily accepted by said insect'smandibles and said randomly oriented jumbled fiber orientation creatingvoids being too small and discontinuous to permit penetration by saidinsects but sufficiently large for said nonwoven to be water permeable,comprising the steps of: a. covering the ground within a center area ofsaid predetermined area with a first of said nonwoven material to form aground side and a surface side to said material; b. covering the groundsurrounding said center area of said predetermined area with a second ofsaid nonwoven material to form a peripheral portion of saidpredetermined area, said peripheral portion having a ground side and asurface side to said material and an outer periphery, c. covering atleast said peripheral portion of said predetermined area with at leastsix inches of a final material or structure, said material thicknessbeing sufficient to prevent said insects from penetrating said materialand the distance from said periphery to said predetermined area issufficient to prevent said insets from forming a colony at said groundside and traveling to said periphery to reach said surface side, therebyprevent insects from transporting food to said colony.
 12. The method ofclaim 11 further comprising the steps of using fibers having a length ofabout 1½ inches.
 13. The method of claim 11 further comprising the stepsof using fibers having a denier of about 1.5.
 14. The method of claim 11wherein said first of said nonwoven material used around said peripheralportion of said predetermined area has a weight per square yard greaterthan the weight per square yard of said second of said nonwoven materialused within said center area of said predefined area
 15. The method ofclaim 11 wherein at least a portion of insects entering said voidsbecome trapped therein and die from lack of water and food.
 16. Themethod of claim 12 wherein said inspects are prevented from penetratingsaid material from said ground side to said surface side.
 17. The methodof claim 12 wherein said inspects are prevented from penetrating saidmaterial from said surface side to said ground side.
 18. The method ofclaim 12 wherein said first of said nonwoven material used around saidperipheral portion of said predetermined area has a weight per squareyard greater than the weight per square yard of said second of saidnonwoven material used within said center area of said predefined area.19. A method of preventing insects from invading a foundation using afabric formed of a needlepunched, nonwoven synthetic material havingomnidirectional fiber orientation and irregular voids, said fibershaving an average fiber diameter at least equal to the diameter easilyaccepted by the insect's mandibles and said voids being too small andtoo discontinuous to permit penetration by said insects but sufficientlylarge for said nonwoven to be water permeable, comprising the steps of:a. preparing the ground for said foundation, said foundation having aperiphery; b. covering said prepared ground with said nonwoven materialto form a ground side, a foundation side and a periphery to saidmaterial; a. constructing said foundation over said nonwoven material;said fabric thickness being sufficient to prevent said insects frompenetrating from said ground side to said foundation side of saidmaterial
 20. The method of claim 20 wherein said periphery of saidnonwoven material is greater than said periphery of said foundation,thereby enabling nonwoven material to cover at least a portion of saidfoundation sides.